Building Segments

Segments let you define audiences based on contact properties and behavior. Once created, a segment can be attached to flows to control who enters, used to filter analytics, or browsed to understand your contact base.

Creating a Segment

Go to Segments in the dashboard sidebar.
Click Create Segment.
Give your segment a name and optional description.
Add one or more filters (see below).
Preview the matching contacts.
Click Save.

Adding Filters

Filters define the criteria that contacts must match to be included in the segment. Each filter has three parts:

Part	Description	Example
Field	The contact property or behavior to check	`product_type`, `properties.country`, `email`
Operator	How to compare the field	`is`, `contains`, `greater_than`
Value	What to compare against	`Standard`, `Singapore`, `100`

Standard Contact Fields

These are fields available on every contact:

Field	Description
`email`	Contact's email address
`first_name`	First name
`last_name`	Last name
`phone`	Phone number
`product_type`	Product category (e.g., Standard, Premium)
`subscription_status`	Email subscription status (subscribed, unsubscribed, complained)
`created_at`	When the contact was first created

Custom Properties

Your contacts may also have custom properties stored in their profile. Access these by prefixing with properties.:

properties.country
properties.language
properties.plan
properties.onboarding_status

The available custom properties depend on what data your application sends with events.

Filter Logic: All vs Any

When you have multiple filters, you need to choose how they combine:

All (AND Logic)

Every filter must match. The contact must satisfy all conditions to be included.

Example: Contacts who are subscribed AND in Singapore AND on the Standard product:

Filter	Operator	Value
`subscription_status`	is	`subscribed`
`properties.country`	is	`SG`
`product_type`	is	`Standard`

Any (OR Logic)

At least one filter must match. The contact is included if any condition is true.

Example: Contacts who are on Standard OR Premium:

Filter	Operator	Value
`product_type`	is	`Standard`
`product_type`	is	`Premium`

Tip

For most segments, "All" (AND) logic is the right choice. Use "Any" (OR) when you want to combine contacts from different groups into one segment.

Exclusion Rules

Exclusion rules let you remove specific groups from a segment, regardless of whether they match the inclusion filters. This is useful for preventing certain contacts from receiving communications.

After adding your inclusion filters, click Add Exclusion Rule.
Configure the exclusion filter (same field/operator/value pattern).
Any contact matching an exclusion rule is removed from the segment, even if they match all inclusion filters.

Example: All subscribed contacts in Singapore, EXCEPT those on the Premium or Unsub product:

Inclusion: subscription_status is subscribed AND properties.country is SG
Exclusion: product_type in Premium, Unsub

Previewing Contacts

Before saving, you can preview how many contacts match your segment:

Click Preview or Evaluate to see the current match count.
Click View Contacts to browse the list of matching contacts.
Adjust your filters if the count is too high or too low.

Note

The preview shows the current count at the time you click. For dynamic segments, this count is recalculated automatically on a regular schedule (typically hourly).

Behavioral Filters

In addition to property-based filters, you can filter contacts based on their event history:

Operator	Description	Example
`has_executed`	Contact has performed this event at least once	`has_executed` `purchase_complete`
`has_not_executed`	Contact has never performed this event	`has_not_executed` `onboarding_complete`

These are powerful for targeting contacts based on what they have or haven't done, not just who they are.

Example: Contacts who signed up but never completed onboarding:

Filter	Operator	Value
`subscription_status`	is	`subscribed`
Event: `onboarding_complete`	has_not_executed	--

Estimating Segment Size

Before saving a segment, you can estimate how many contacts would match your current filters:

After configuring your filters and exclusion rules, click Estimate.
The builder shows the total matching count and a per-rule breakdown, so you can see which individual filters are the most or least restrictive.
Adjust your filters based on the counts until you have the right audience size.

This runs a lightweight count query without creating the segment, so you can iterate quickly.

Archiving and Unarchiving

If you have segments you are not currently using but want to keep for later, archive them instead of deleting:

Open the segment you want to archive.
Click Archive.
The segment is hidden from the default list view but still exists.

To find archived segments, toggle the Show Archived filter on the Segments list page.

To restore an archived segment:

Find the segment in the archived list.
Click Unarchive.
The segment returns to the active list and can be used in flows again.

Tip

Archiving is reversible. Deleting is permanent. When in doubt, archive.

Duplicating a Segment

To create a new segment based on an existing one:

Open the segment you want to copy.
Click Duplicate.
A new segment is created with the name "Original Name (copy)" and the same filters, exclusion rules, and tags.
Edit the duplicate to adjust the filters for your new use case.

Membership History

Synapse records the segment size each time it is evaluated, creating a trend over time. To view the membership history:

Open a segment.
Look at the Membership Trend graph.
The graph shows how the contact count has changed over the selected time range (up to 365 days).

This is useful for understanding whether your audience is growing, shrinking, or stable.

Segment Usage

To see which flows currently reference a segment:

Open the segment.
Check the Used By section, which lists all flows that target this segment along with their status (active, draft, paused).

Warning

Before deleting or significantly changing a segment's filters, check its usage. Active flows that depend on the segment will be directly affected.

Using Segments in Flows

Once you've created a segment, you can attach it to any flow:

Open the flow you want to restrict.
In the flow settings, open the Segment dropdown.
Select your segment.

Now, only contacts who match the segment will enter the flow -- even if the trigger event fires for other contacts.

Next Steps

See the full list of Filter Operators
Learn Best Practices for organizing and naming segments

Looking for the API?

If you prefer to create and manage segments programmatically, see the Segments API Reference.